This invention relates generally to gyroscopes and more particularly to an improved caging mechanism which serves to effect caging of the inner gyroscope gimbal.
Gyroscopes used in avionics have long been equipped with caging mechanisms which are used to "cage" or rotate the inner gimbal to the orientation necessary for proper operation of the instrument. For example, in directional gyroscopes, the inner gimbal must be caged such that the spin axis of the rotor is oriented horizontally. Following release of the caging mechanism, rotation of the rotor retains the inner gimbal in the proper horizontal orientation during operation of the gyroscope instrument.
Typically, existing caging mechanisms are highly complex devices having a large number of cooperating mechanical parts such as pivot plates, cams, caging arms and the like. Aside from complicating the gyroscope unduly and adding to the expense and to the assembly difficulties, these components also require precision machining and have close tolerance requirements. Furthermore, frequent replacement and/or repair of the parts is necessary and the likelihood of mechanical problems is increased substantially. Due to the tendency for existing caging mechanisms to cage the inner gimbal rather abruptly, the gimbal bearings and other sensitive components of the instrument are exposed to severe stress which can cause significant damage. Another difficulty results from the high angular momentum that builds up in the spinning rotor. The gyroscope strongly resists attempts to rotate the inner gimbal during caging, and, due to the gyroscope principle, the outer gimbal and its bearings are subjected to forces which can lead to damage, particularly to the sensitive low friction bearings. Additional problems associated with the caging mechanisms that have been used in the past include lack of reliability, jerky operation in both the caging action and release, and the possibility of inadvertent interference with the gimbals due to vibration or other forces acting on the caging device.